WO2017031306A1 - Procédés pour fournir une neurostimulation optimisée - Google Patents

Procédés pour fournir une neurostimulation optimisée Download PDF

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Publication number
WO2017031306A1
WO2017031306A1 PCT/US2016/047535 US2016047535W WO2017031306A1 WO 2017031306 A1 WO2017031306 A1 WO 2017031306A1 US 2016047535 W US2016047535 W US 2016047535W WO 2017031306 A1 WO2017031306 A1 WO 2017031306A1
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Prior art keywords
waveform
waveforms
electrodes
pulse
frequency
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PCT/US2016/047535
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English (en)
Inventor
Susan J. HARKEMA
Yangsheng Chen
Robert S. Keynton
Douglas J. Jackson
John Naber
Thomas Roussel
Manikandan RAVI
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University Of Louisville Research Foundation, Inc.
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Priority to US15/752,280 priority Critical patent/US11007368B2/en
Publication of WO2017031306A1 publication Critical patent/WO2017031306A1/fr
Priority to US17/230,280 priority patent/US20210228885A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/3605—Implantable neurostimulators for stimulating central or peripheral nerve system
    • A61N1/36128—Control systems
    • A61N1/36146—Control systems specified by the stimulation parameters
    • A61N1/36182—Direction of the electrical field, e.g. with sleeve around stimulating electrode
    • A61N1/36185—Selection of the electrode configuration
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/02—Details
    • A61N1/04—Electrodes
    • A61N1/05—Electrodes for implantation or insertion into the body, e.g. heart electrode
    • A61N1/0551—Spinal or peripheral nerve electrodes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/3605—Implantable neurostimulators for stimulating central or peripheral nerve system
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/3605—Implantable neurostimulators for stimulating central or peripheral nerve system
    • A61N1/36128—Control systems
    • A61N1/36146—Control systems specified by the stimulation parameters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/3605—Implantable neurostimulators for stimulating central or peripheral nerve system
    • A61N1/36128—Control systems
    • A61N1/36146—Control systems specified by the stimulation parameters
    • A61N1/36167—Timing, e.g. stimulation onset
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/3605—Implantable neurostimulators for stimulating central or peripheral nerve system
    • A61N1/36128—Control systems
    • A61N1/36146—Control systems specified by the stimulation parameters
    • A61N1/36167—Timing, e.g. stimulation onset
    • A61N1/36171—Frequency
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/3605—Implantable neurostimulators for stimulating central or peripheral nerve system
    • A61N1/36128—Control systems
    • A61N1/36146—Control systems specified by the stimulation parameters
    • A61N1/3615—Intensity

Definitions

  • Embodiments of the present invention relate to methods for neurostimulation therapy for spinal cord injury. More particularly, embodiments of the present invention relate to methods for providing multiple independent, simultaneous waveforms in neurostimulation therapy while minimizing or substantially eliminating undesirable interactions between the waveforms.
  • SCI Serious spinal cord injuries
  • ES epidural stimulation
  • High density epidural stimulating electrode arrays can provide spatially selective stimulation to regions of the spinal cord to facilitate or cause muscle movement.
  • SCI and other conditions may benefit from the delivery of stimulus intended to enable or excite multiple neurological responses using an implantable neurostimulator.
  • a targeted neurological function such as blood pressure, may respond to a particular electrical stimulus or waveform at a specific location, amplitude, frequency, pulse width or a combination thereof.
  • Other functions such as muscle flexon, may require a different waveform to produce the desired response.
  • the different stimulus signals may interfere and prevent the desired responses or even cause an undesired and potentially dangerous overstimulated condition.
  • the circuit shown in FIG. 1 is a simplified model of four electrodes being stimulated using two different waveforms for neurostimulation.
  • a first waveform connects to electrode pair 4 and 3, while a second waveform connects to electrode pair 2 and 1.
  • Node R is common to all electrodes, since all electrodes are in a common conductive medium, e.g., tissue and fluid. Interactions between each pair of electrode sets or waveforms can occur when electrodes are not isolated from connecting circuits. These coupled interactions between waveforms with overlapping pulses can add constructively or destructively to each other, depending upon if each pulse is in the charging or discharging phase.
  • Methods for minimizing undesirable interactions between waveforms, particularly in neurostimulation therapy for spinal cord injury.
  • Methods include modifying characteristics of independent, simultaneous waveforms with overlapping pulses, and hardware-based solutions for minimizing or substantially eliminating interactions between pulses.
  • FIG. 1 is a schematic of an exemplary circuit for providing two simultaneous and independent waveforms.
  • FIG. 2 is a schematic displaying pulses of waveforms Wl and W2a and phase optimized waveform W2b. Individual pulses are depicted as lines, with dotted lines depicting pulse collisions between Wl and W2a which are avoided in phase optimized waveform W2b.
  • FIG. 3 is a schematic displaying pulses of waveform Wl and frequency optimized waveform W2. Individual pulses are depicted as lines, with dotted lines depicting pulse collisions avoided by frequency optimization of W2.
  • FIG. 4 is a chart depicting five simultaneous waveforms, with optimized and non- optimized versions of the waveforms superimposed.
  • FIG. 5A is a chart depicting three simultaneous waveforms generated by a neurostimulator with (top) a frequency of 55 Hz and a pulse width of 200 ⁇ , (middle) a frequency of 33 Hz and a pulse width of 750 ⁇ , and (bottom) a frequency of 25 Hz and a pulse width of 1000 ⁇ .
  • FIG. 5B is a chart depicting pulse collisions between the waveforms of FIG. 5 A, with the top line displaying collisions between all three waveforms, the next lower line displaying collisions between the 33 Hz and 55 Hz waveforms, the next lower line displaying collisions between the 25 Hz and 55 Hz waveforms, and the bottom line displaying collisions between the 25 Hz and 33 Hz waveforms.
  • FIG. 6A is a chart depicting the three waveforms of FIG. 5 A after phase optimization of the 33 Hz waveform.
  • FIG. 6B is a chart depicting pulse collisions between the waveforms of FIG. 6A, with the top line displaying collisions between all three waveforms, the next lower line displaying collisions between the 33 Hz and 55 Hz waveforms, the next lower line displaying collisions between the 25 Hz and 55 Hz waveforms, and the bottom line displaying collisions between the 25 Hz and 33 Hz waveforms.
  • FIG. 7A is a chart depicting the three waveforms of FIG. 5 A after pulse width optimization of the three waveforms.
  • FIG. 7B is a chart depicting pulse collisions between the waveforms of FIG. 7A, with the top line displaying collisions between all three waveforms, the next lower line displaying collisions between the 33 Hz and 55 Hz waveforms, the next lower line displaying collisions between the 25 Hz and 55 Hz waveforms, and the bottom line displaying collisions between the 25 Hz and 33 Hz waveforms.
  • FIG. 8A is a chart depicting the three waveforms of FIG. 5 A after pulse width optimization and phase optimization of the three waveforms.
  • FIG. 8B is a chart depicting pulse collisions between the waveforms of FIG. 8A, with the top line displaying collisions between all three waveforms, the next lower line displaying collisions between the 33 Hz and 55 Hz waveforms, the next lower line displaying collisions between the 25 Hz and 55 Hz waveforms, and the bottom line displaying collisions between the 25 Hz and 33 Hz waveforms.
  • FIG. 9A is a flowchart depicting an exemplary method for optimizing waveforms.
  • FIG. 9B is a flowchart depicting an exemplary phase optimization process.
  • FIG. 10 is a schematic of an exemplary circuit including two separate and isolated power sources.
  • FIG. 11 A depicts a schematic of an electrode array with two independent power supplies.
  • FIG. 1 IB depicts an oscilloscope trace from activation of the first electrode array shown in FIG. 11 A.
  • FIG. l lC depicts a schematic of a second electrode array with two independent power supplies.
  • FIG. 1 ID depicts an oscilloscope trace from activation of the second electrode array shown in FIG. 11C.
  • FIG. 12A depicts a schematic of a third electrode array.
  • FIG. 12B depicts a first oscilloscope trace from activation of the third electrode array shown in FIG. 12A.
  • FIG. 12C depicts a second oscilloscope trace from activation of the third electrode array shown in FIG. 12A.
  • FIG. 13 depicts a series of electrode arrays designated X, S I, S2 and I.
  • FIG. 14 includes four panels depicting oscilloscope traces from activation of electrode arrays X, SI, S2 and I shown in FIG. 13.
  • invention within this document herein is a reference to an embodiment of a family of inventions, with no single embodiment including features that are necessarily included in all embodiments, unless otherwise stated. Further, although there may be references to “advantages” provided by some embodiments of the present invention, it is understood that other embodiments may not include those same advantages, or may include different advantages. Any advantages described herein are not to be construed as limiting to any of the claims.
  • the present invention comprises methods for minimizing undesirable interactions between waveforms, particularly in nerve stimulation therapy for spinal cord injury.
  • an electrode array comprising a plurality of electrodes disposed on a flexible biocompatible material.
  • the electrodes comprise one or more biocompatible metals or alloys, as known in the art.
  • Sets of electrodes within the array generate waveforms, the electrode array being configured to generate at least two simultaneous waveforms, each waveform having a frequency, a pulse width, a phase and at least one pulse.
  • the electrode array and resulting waveforms may be optimized to reduce overlapping pulses between waveforms by software or hardware-based solutions.
  • waveforms are optimized by at least one of altering the phase of the waveform, altering the frequency of the waveform, altering the pulse width of the waveform, delaying a pulse of the waveform and blanking a pulse of the waveform.
  • the first method of waveform optimization is phase optimization. This method uses a computed delay to find the optimal position of waveforms relative to each other for the purpose of avoiding as many overlapping pulses as possible. Waveforms are assigned a priority and their phase is adjusted to optimize the higher priority waveform first. Referring to FIG. 2, the top waveform (Wl) is designated the high priority waveform and remains unchanged. A lower priority waveform, W2, has a designated phase and collisions
  • W2a shows three collisions with Wl , as indicated by the vertical dashed lines, where pulses from W2a overlap with pulses from Wl .
  • the waveform then has its phase delayed by an increment and the collisions are recounted in W2b.
  • the phase delay results in no collisions between W2b and Wl in the time period shown.
  • the delay that results in the fewest number of collisions is considered the optimized phase delay and can be set to automatically be adopted by the system or controlled manually.
  • the lower priority offending pulse can either be "blanked” or eliminated, or phase shifted forward or backward in time to avoid overlapping, depending on which option is therapeutically preferable for the patient. Additional waveforms of lower priority can be tested against Wl and the optimized W2b to obtain the optimal delay for the additional waveforms.
  • the steps in this method can be summarized as follows: (1) count the number of collisions between two waveforms, Wl and W2, over a period of time T; (2) delay the lower priority waveform, in this case W2, an increment and recount collisions in period T; (3) repeat steps 1 and 2 until the increment reaches the period of the highest frequency waveform being compared; (4) adopt the delay (also referred to as "phase shift") that results in the lowest number of collisions; and (5) blank specific pulses from the W2 (the lower priority waveform) to remove the collision in order to produce a corrected W2.
  • steps 1-5 are repeated such that the additional waveform is compared to Wl and corrected W2, a phase shift is adopted for the additional waveform that minimizes collisions with higher priority waveforms, and overlapping pulses are blanked to produce a corrected additional waveform.
  • the steps may be repeated as needed for further simultaneous waveforms.
  • a second method of waveform optimization is an alternating frequency approach.
  • the frequency of a lower priority waveform is varied to avoid overlapping with the higher priority waveform.
  • the lower priority waveform varies between two predetermined frequencies to avoid collisions with a higher priority waveform. Combining two frequencies on one waveform allows an interval to form so that no blanking or delayed reset is required. This two frequency approach eliminates a missing pulse and hence small gaps with no active stimulus.
  • Wl is the higher priority waveform and its frequency does not change.
  • the period of Wl is 7x.
  • W2 is a lower priority waveform that is allowed to change between two fixed frequencies with periods 4X and 5X.
  • the other frequency is selected. That is, if a pulse overlap is expected to occur while maintaining the 4X period, the W2 waveform is transitioned to the 5X period prior to the overlap to avoid the collision.
  • the waveform is transitioned back to the 4X period.
  • the choice of frequencies may be based on the effectiveness of the chosen frequencies on neurostimulation, in that a small frequency change may not be detrimental to therapy, and based on selecting frequencies which correct the timing and minimize the number of collisions. While this method is primarily designed to avoid pulse collisions, varying the frequency of a waveform may also be used to intentionally create a desired neurostimulatory response.
  • a typical neurostimulation pulse includes a wait period (X), charge pulse (1), inter-pulse delay (.05), a recharge pulse (4), and a shorting period (4).
  • the numbers correspond to the relative length of that portion of the pulse, with the length of the wait period being variable.
  • the duration of the pulse and subsequent delay, recharge pulse and shorting period are determined by neurological needs and the need to balance charge on the electrode. In some cases it is possible to shorten pulses or parts of pulses to help eliminate overlap conditions between waveforms. In particular, the charge balance portion of the pulse (i.e., the recharge pulse and shorting period) may be reduced.
  • the recharge period could be reduced from (4) to (3) and the shorting period from (4) to (2) resulting in an approximate 33% reduction in duration for the active portion of the pulse.
  • Brief periods of charge balance time optimization may be used to allow spacing between pulses from different waveforms and reduce the need to blank a pulse.
  • the pulse collision between five simultaneous waveforms can be reduced by over 90% by just changing the adjustable recharge period from (4) to (1).
  • the recharge period is visible as the relatively small period of decreased amplitude directly following each pulse. Decreasing the recharge period increases the available time window from only 3.5% to 65% to incorporate global shorting and to minimize any residual electrode charge.
  • Commercial neurostimulators typically use a recharge pulse length of (4) to amply ensure that charge has been removed from the electrode and to minimize power consumption.
  • the ability to vary the width of the recharge pulse and shorting pulse provides clinicians with tremendous flexibility in managing waveforms to reduce overlaps.
  • a system may operate in a high power mode with a short recharge pulse length of (1) when managing multiple complex waveforms with long charge pulses and many pulse overlaps, and switch to a low power mode using a long recharge pulse length of (4) when managing few waveforms with short charge pulses and few pulse overlaps.
  • a fourth method of managing waveform interactions is by blanking a lower priority waveform.
  • this method upon detection, calculation or prediction of an overlap of pulses between a higher priority waveform and a lower priority waveform, the pulse of the lower priority waveform is blanked.
  • blanking a pulse can result in a small signal void that may be undesirable.
  • Another option to blanking an overlapping pulse is to add a pulse to delay the waveform so it can be reset to restart the waveform in its initial position. This is similar to the two frequency approach described in the second method. However, in this case, the frequency that is produced by the corrected delay occurs for one period and is calculated on a collision by collision basis.
  • FIGs. 5-8 display the results of these various methods in optimizing three
  • FIG. 5A depicts pulses from the three waveforms, each with recharge period of 4 and a shorting period of 4.
  • FIG. 5B depicts collisions between pulses from the three waveforms.
  • the rate of pulse collisions between the 25 Hz and 33 Hz waveforms is 52%
  • the rate of pulse collisions between the 25 Hz and 55 Hz waveforms is 60%
  • rate of pulse collisions between the 33 Hz and 55 Hz waveforms is 67%.
  • FIG. 6A depicts the three waveforms from FIG. 5A after undergoing phase optimization.
  • the 33 Hz waveform has been delayed to decrease collisions with the highest priority waveform, that being the 55 Hz waveform.
  • the frequencies, pulse widths, recharge periods and shorting periods remain unchanged.
  • the number of collisions between pulses in the 55 Hz and 33 Hz waveforms has decreased significantly.
  • FIG. 7A depicts the three waveforms from FIG. 5A after undergoing charge balance time optimization. The recharge period has been decreased to (1) and the shorting period has been decreased to (0).
  • the frequencies and onset times of the waveforms remain unchanged, as do the pulse widths of the charging pulses.
  • the number of collisions between pulses has decreased significantly for all three waveforms.
  • the rate of pulse collisions between the 25 Hz and 33 Hz waveforms has decreased to 12%
  • the rate of pulse collisions between the 25 Hz and 55 Hz waveforms remains has decreased to 20%
  • rate of pulse collisions between the 33 Hz and 55 Hz waveforms has decreased to 33%.
  • Further reduction of collisions may be achievable by phase optimization of the 25 Hz waveform against the 55 Hz waveform and the optimized 33 Hz waveform.
  • FIG. 8A depicts the three waveforms from FIG. 5A after undergoing charge balance time optimization and phase optimization.
  • the recharge period has been decreased to (1) and the shorting period has been decreased to (0) for all three waveforms.
  • the 33 Hz waveform has been delayed to decrease collisions with the 55 Hz waveform, and
  • the 25 Hz has been delayed to decrease collisions with the 55 Hz and 33 Hz waveforms.
  • the frequencies of the waveforms remain unchanged.
  • the number of collisions between pulses has decreased significantly for all three waveforms.
  • the rate of pulse collisions between the 25 Hz and 33 Hz waveforms has decreased to 8%, and all pulse collisions between the 55 Hz waveform and the other two waveforms have been eliminated.
  • the remaining overlapping pulses between the 25 Hz and 33 Hz waveforms may be blanked or delayed in the lower priority waveform to eliminate all overlaps.
  • the priority of waveforms may be changeable.
  • Wl is defined as the high priority waveform and thus no alterations such as blanking, phase shift, delay or frequency shift are applied to that waveform.
  • IPG implantable pulse generator
  • Pulse collisions are typically avoided to isolate patient stimuli and maintain a balanced charge on neurostimulator electrodes.
  • a purposeful pulse collision may be used to determine details about the equivalent circuit of the array or study the impact of field shapes on neuro responses. For this reason it may be desirable to generate collisions under controlled conditions.
  • the first four methods of optimization disclosed herein may be implemented in software controlling an implanted neurostimulator.
  • a technical user interface such as a general purpose computer, or a patient user interface (PUI), such as a portable dedicated computing device, a smartphone or other portable computing device, run software communicatively coupled to the implanted neurostimulator and capable of adjusting the characteristics of waveforms generated by the neurostimulator.
  • the clinicians initially use the TUI in a clinical setting to evaluate the SCI patients to identify the set of waveforms necessary to generate responses from the patient, such as standing, leg flexion, leg extension, blood pressure control, bladder control, etc. Overlapping pulses often occur when generating multiple simultaneous pulses that have different frequencies that are not harmonically related to each other, as shown in FIGs. 5A and 5B.
  • the optimum set of waveforms and their characteristics are unique to each patient.
  • the clinician uses the TUI to identify waveforms needed by a patient to elicit a desired response, such as waveforms stimulating leg muscles to elicit a walking motion, in conjunction with waveforms maintaining the patient's blood pressure at a safe level.
  • the clinician determines the priority of the various wave forms based on the patient's physiological needs. For example, waveforms maintaining blood pressure are more critical to the patient's health than waveforms eliciting a walking motion so blood pressure-related waveforms will be designated as higher priority than walking-related waveforms.
  • these optimized waveforms can be transferred from the TUI to the PUI for the patient to activate at the patient's discretion.
  • the patient uses the PUI to select what motor responses, such as standing or walking, or physiological responses, such as blood pressure control, that he or she wishes to enact, and the PUI instructs the patient's implanted neurostimulator to enact the predetermined waveforms to enact such responses in the patient.
  • PUI is configured such that the patient can only run waveforms optimized by the TUI, and the patient cannot create or modify waveforms or combinations thereof.
  • the TUI runs software is designed to display waveforms and show what percentage of overlap exists and where the overlap occurs in time, as shown in FIGs. 5-8.
  • the clinician is then presented options as described in methods one through four to reduce or eliminate the number of overlapping pulses.
  • the waveforms are optimized, they are transmitted from the TUI to a base station, which wirelessly transmits the data to the IPG.
  • the first four methods of optimization disclosed herein may be implemented in the hardware of the neurostimulator such as, by algorithmic detection of pulse collisions and implementation of methods to minimize collisions. In such
  • unoptimized waveforms are transmitted to the neurostimulator and a controller, such as a microprocessor, included in the neurostimulator optimizes the waveforms before delivery of electric stimulation to the patient.
  • a controller such as a microprocessor
  • FIGs. 9A and 9B provide an embodiment of a method for optimizing waveforms, with FIG. 9B providing an exemplary initial phase delay optimization program, as referenced in step 3 in the flowchart of FIG. 9A.
  • the exemplary program depicted in FIG. 9B is specific to only the initial phase delay optimization for minimization of pulse overlaps, and, in other embodiments, significantly more complex programs would be used.
  • a user identifies two or more waveforms for delivery to a patient, and designates electrodes to provide the waveforms, setting pulse width, frequency, amplitude, waveform priority, onset and offset times, and other relevant settings.
  • the user sets a recharge period for active charge balance for the activating electrodes and sets a local shorting period for passive charge balance for the activating electrodes.
  • the recharge period is typically (1), (2) or (4), with (4) being the most common initial value of an unoptimized waveform.
  • the shorting period is typically (0), (1), (2) or (4), with (4) being the most common initial value of an unoptimized waveform.
  • step 14 the user performs a phase optimization to add a delay to waveforms, apart from the highest priority waveform, as explained in further detail in connection with FIG. 9B.
  • step 16 the user reviews the simulated collisions after phase optimization. If the percentage of pulses colliding is greater than a predetermined value, such as greater than 20%, greater than 25%, greater than 30%, or greater than 50%, then optimization is not performed and the process is begun again using non-identical waveforms.
  • step 18 pulses on lower priority waveforms which collide with pulses on higher priority waveforms are blanked.
  • the optimized waveforms are transmitted to the neurostimulator.
  • the optimized waveforms are transmitted from the TUI to a base station by a wired or wireless connection, then transmitted by a wireless connection between the base station and the neurostimulator.
  • the user is a clinician or other medical professional trained in neurostimulation techniques.
  • the waveforms are optimized by phase optimization, pulse width optimization, frequency optimization, blanking colliding pulses, or a combination thereof.
  • the waveforms are optimized by performing at least two different optimization processes.
  • FIG. 9B depicts an exemplary phase optimization process for two waveforms as performed in step 14 of the flowchart shown in FIG. 9 A.
  • the two waveforms differ in frequency, and are designated as the high frequency waveform and the low frequency waveform.
  • the wavelength of the high frequency waveform is calculated using techniques known in the art (in signal processing, wavelengths are typically measured in units of time, not distance).
  • a first counting variable is assigned a value of zero.
  • step 26 is a Boolean determination of whether the first counting variable is less than the calculated wavelength: if false, the process proceeds to step 28 and outputs the optimum shifting position, and if true, the process proceeds to step 30.
  • a second counting variable is assigned a value of zero.
  • Subsequent step 32 is a Boolean determination of whether the second counting variable is less than the calculated wavelength: if false, the process proceeds to step 34, and if true, the process proceeds to step 36.
  • step 34 first counting variable is increased by a first increment, then the process returns to step 26.
  • step 36 the onset time of the low frequency waveform is delayed by the sum of the first counting variable and the second counting variable.
  • step 38 the number of pulse collisions between the high frequency waveform and delayed low frequency waveform is calculated.
  • Subsequent step 40 is a Boolean determination of whether the number of collisions calculated immediately prior in step 38 is less than the number of previously calculated collisions: if false, the process proceeds to step 42, and if true, the process proceeds to step 44.
  • step 42 the second counting variable is increased by a second increment, then the process returns to step 32.
  • step 44 the optimum shifting position (initially set as zero) is defined as the sum of the first counting variable and the second counting variable, then the process proceeds to step 42 and continues cycling.
  • increments of shifting ranging from no shifting to shifting the entire wavelength of the high frequency waveform have been evaluated, and the outputted optimum shifting position is the shifting position which resulted in the lowest number of collisions.
  • the process depicted in FIG. 9B may be repeated to optimize multiple waveforms. For example, the process may be run a first time to optimize a second- highest frequency waveform against a highest frequency waveform. The process may subsequently be run a second time to optimize a third-highest frequency waveform against the highest and second-highest frequency waveforms. The process may be run additional time to optimize still lower frequency waveforms against higher frequency waveforms until some or all of the simultaneous waveforms in a given neurostimulation have been optimized. Stepwise evaluation processes similar to that shown in FIG. 9B may be used for pulse width optimization, frequency optimization and blanking pulses to reduce pulse collisions.
  • Embodiments of the present invention relate to hardware-dependent methods of managing waveform interactions.
  • independent and isolated power supplies are used to correct the overlapping pulse issue.
  • FIG. 10 an exemplary electrode diagram is shown including two separate and isolated power sources, PS 1 and PS2, which are connected to the current sources by dotted lines.
  • the electrodes 1, 2, 3, 4, 5 and 6 share a single common node R, there is only one connection, so there is no return path for current and this stimuli between sections A and B remain isolated.
  • This method requires a separate and isolated power source for each electrode group containing common frequencies and pulse widths.
  • group A has four electrodes 1, 2, 3 and 4 with a common first frequency and first pulse width
  • group B has two electrodes 5 and 6 with a common second frequency and second pulse width.
  • the first and second frequencies are non-identical.
  • the first and second pulse widths are non-identical. This method depends upon the accuracy of the common node model for the electrode array. If electrodes of section A are in close physical proximity to electrodes of section B, the accuracy of the model may degrade and some interaction between the waveforms, also referred to as "cross talk," may occur.
  • undesirable cross talk occurs when adjacent electrodes are powered by separate and isolated power sources. In other embodiments, undesirable cross talk occurs when electrodes powered by a separate and isolated power source are located within 0.5 cm, within 1.0 cm, or within 1.5 cm of electrodes powered by another separate and isolated power source.
  • FIG. 11A depicts an array of electrodes wherein a pair of electrodes at the top of the array, as indicated by a grey oval, are stimulated by a first IPG and another pair of electrodes at the bottom of the array, as indicated by another grey oval, are stimulated by a second IPG.
  • FIG. 1 IB depicts an oscilloscope trace from the bottom electrode pair, which displays no evidence of waveform interaction from the separate IPG stimulating the top electrode pair.
  • FIG. 11C depicts an array of electrodes including two adjacent trios of electrodes, each indicated by grey ovals, and each stimulated by separate IPGs.
  • FIGs. 11C and 1 ID depicts an oscilloscope trace from one of the trios of electrodes.
  • the large peaks in the scope trace represent pulses from the traced electrodes, and the small peaks indicate pulses from the adjacent electrodes.
  • FIGs. 11C and 1 ID indicate that, even when isolated power supplies are used, cross talk can still occur between closely spaced electrodes.
  • FIG. 12A depicts an array of electrodes wherein a pair of electrodes at the bottom of the array and a pair of electrodes at the top of the array are stimulated using a single IPG having non-isolated power supplies.
  • FIG. 12B shows cross talk between the top and bottom electrode pairs, while FIG. 12C shows no cross talk.
  • FIGs. 11 A - 12C indicate that waveform interactions can be avoided by stimulating electrodes using independent and isolated power supplies when those electrodes are not in close physical proximity to each other.
  • a sixth method of managing waveform interactions includes the use of anodes or cathodes at a fixed potential to provide shielding of the electric field between independent and simultaneous waveforms.
  • Using common ground electrodes physically positioned between stimulation electrodes to shield and separate the stimulation electrodes can effectively compare to managing waveform interactions by using isolated power supplies. It can minimize the interference of two overlapping pulses from two different stimulation electrodes. Test results show that the effectiveness of such shield can compare to the results of using electrodes with two isolated power supplies.
  • FIG. 13 depicts five schematic electrode arrays labeled X, SI, S2, CI and C2.
  • current i flows to stimulation cathode electrodes on the left side of the array, and all anodes have equal potential with the ground.
  • Current is measured in electrodes on the right side of the array, whereby measured current indicates current leakage between electrodes.
  • Additional anodes serving as ground electrodes are positioned between the stimulation and measurement electrodes in arrays SI and S2 serving as shielding electrodes.
  • Additional anodes serving as ground electrodes are also present in arrays CI and C2, but such additional anodes are not positioned between the stimulation and measurement electrodes. No additional anodes are present in array X.
  • Each array uses a single, non-isolated power supply.
  • FIG. 14 depicts waveforms from oscilloscope
  • array S2 In array S2, 4.312 mA of current are generated across the 2 electrodes on the left and 0.575 mA are measurable on the 2 electrodes on the right, which evidences a current leakage of 13% in the array including two shielding electrodes.
  • array CI 4.246 mA of current are generated across the 2 electrodes on the left and 0.775 mA are measurable on the 2 electrodes on the right, which evidences a current leakage of 18% in the array including 2 non-shielding electrodes.
  • One aspect of the present invention pertains to a method for providing optimized neurostimulation, including providing an electrode array configured to generate at least two simultaneous waveforms, each waveform including a frequency, a charge balance time, a phase and at least one pulse; optimizing at least one of the at least two simultaneous waveforms to reduce pulse collisions by at least one of altering the phase of the waveform, altering the frequency of the waveform, optimizing the charge balance time of the waveform, delaying a pulse of the waveform, and blanking a pulse of the waveform; and activating the electrode array to generate the at least two simultaneous waveforms.
  • Another aspect of the present invention pertains to a method for providing optimized neurostimulation, including providing an electrode array comprising a plurality of electrodes, wherein the plurality of electrodes are divided into at least two groups of electrodes, and wherein the electrode array is configured to generate at least two
  • simultaneous waveforms providing a power source for each group of electrodes, each power source being electrically isolated and physically separate from each other power source; and activating the electrode array to generate the at least two simultaneous waveforms.
  • a further aspect of the present invention pertains to a method for providing optimized neurostimulation, including providing an electrode array comprising a plurality of electrodes; grouping the plurality of electrodes into a first group including at least one electrode configured to generate a first waveform, a second group including at least one electrode configured to generate a second waveform, and a third group including at least one electrode with a fixed potential, wherein the third group is located between the first group and the second group; and activating the electrode array to generate at least one of the first waveform and the second waveform.
  • the method further comprising identifying one of the at least two simultaneous waveforms as a high priority waveform, and wherein the optimizing is applied to a waveform other than the high priority waveform.
  • optimizing includes at least two of altering the phase of the waveform, altering the frequency of the waveform, optimizing the charge balance time of the waveform, delaying a pulse of the waveform, and blanking a pulse of the waveform.
  • optimizing the charge balance time of the waveform includes at least one of increasing a recharge period, decreasing a recharge period, increasing a shorting period, and decreasing a shorting period.
  • optimizing the charge balance time of the waveform includes at least one of decreasing a recharge period and decreasing a shorting period.
  • the method further comprising transmitting the at least two simultaneous waveforms to a receiver in communication with a processor, the processor being in communication with the electrode array.
  • the electrode array is implanted in a patient.
  • each of the at least two simultaneous waveforms includes non-identical frequencies.
  • altering the phase of the waveform includes delaying the phase of the waveform.
  • altering the frequency of the waveform includes increasing or decreasing the frequency of the waveform.
  • each electrode within the group shares a common frequency and pulse width.
  • the electrode array is implanted in a patent.
  • first group, the second group, and the third group each include at least two electrodes.

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Abstract

L'invention concerne des procédés de thérapie par neurostimulation pour une lésion de la moelle épinière. Plus particulièrement, la présente invention concerne des procédés de thérapie par neurostimulation pour une lésion de la moelle épinière. Plus particulièrement, la présente invention concerne des procédés permettant de produire de multiples formes d'onde simultanées indépendantes dans une thérapie par neurostimulation tout en réduisant au maximum ou en éliminant sensiblement les interactions indésirables entre les formes d'onde.
PCT/US2016/047535 2015-08-19 2016-08-18 Procédés pour fournir une neurostimulation optimisée WO2017031306A1 (fr)

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US11291843B2 (en) * 2018-12-07 2022-04-05 Medtronic, Inc. Changing electrical stimulation

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WO2010067360A2 (fr) * 2008-12-09 2010-06-17 Nephera Ltd. Stimulation de l'appareil urinaire
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US20080049376A1 (en) * 1998-11-04 2008-02-28 Greatbatch Ltd. Non-ferromagnetic tank filters in lead wires of active implantable medical devices to enhance mri compatibility
WO2010067360A2 (fr) * 2008-12-09 2010-06-17 Nephera Ltd. Stimulation de l'appareil urinaire
US20150196767A1 (en) * 2013-12-22 2015-07-16 Zaghloul Ahmed Trans-spinal direct current modulation systems

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